This invention relates to a lining of a brake band used for a speed change gear for an automobile, an agricultural machine, a building machine and the like.
FIG. 15 is a perspective view showing a conventional brake band 20 which comprises a curved strap 11 and a lining 12 bonded to the inner surface of the strap by an adhesive. Reference numerals 13 and 14 denote mounting plates, reference numerals 15 and 16 brackets, and reference numeral 17 an oil hole. The lining 12 is made of a wet frictional material containing lubricating oil.
The brake band in an automatic speed change gear operates instantaneously (for about 0.5 to 1 seconds). At this time, although frictional heat is generated between the brake band and its mating drum, the lubricating oil contained in the wet frictional material (lining 12) oozes out from the interior of the lining as a result of elastical deformation or compression of the lining subjected to the friction, and the thus oozing lubricating oil disperses the frictional heat. This effect restrains a temperature rise of the frictional surface. However, with a higher output power and a higher rotational speed of an engine, the conditions of use of the brake band for the automatic speed change gear have been becoming severer. Under the circumstances, it has now been difficult for conventional lining materials to provide sufficiently satisfactory durability and speed change performance as required. Heretofore, the lining material itself has been modified in order to improve the durability of the brake band and a speed change performance. However, if there is no suitable material to meet the requirements a new material must be developed. However, the development of such a lining material requires much time and cost, and this cannot be achieved soon.